Areno [E]indols, preparation method and application as intermediates in the synthesis of products with antitumoral activity

ABSTRACT

The areno[e]indols have the formula (I). The methods comprises: (a) reacting (VI) with an aldehyde Ar&#34;--CHO to obtain (VII); (b) oxidizing (VII) to yield the cetone (VIII); (c) reating (VIII) with a strong base and thereafter with an acycle chloride ClCOR, to produce (IX); (d) subjecting to a photochemical cyclization (IX) to produce (I). In said formulas Ar is phenyl or substituted phenyl; Ar&#39; is radical (i) or (ii); R is an acyle group, Ar&#34; is a phenyl, pyrolyl, furanyl or thiophenyl group substituted up to three times by any of the radials R, R 1 , R 2 , or R 3 . The compounds (I) are useful as intermediates in the synthesis of hexahydroareno(e)cyclopropa(c)indol-4-ones with antitumoral activity.

This is a continuation of international application Ser. No.PCT/ES93/00078, filed Sep. 22, 1993.

This is a continuation of international application Ser. No.PCT/ES93/00078, filed Sep. 22, 1993.

TECHNICAL FIELD OF THE INVENTION

The present invention is comprised in the technical field of theproduction of compounds with antitumoral activity.

Specifically, the present invention refers to the obtainment of newareno indols, useful in the synthesis ofhexahydroareno[e]cidopropa[c]indol-4-ones with antitumoral properties.

PRIOR ART OF THE INVENTION

Obtaining phenantrenes by oxidative photochemical cycling of stilbenesis a synthetic method largely used as can be seen in the review of F. B.Mallory and C. W. Mallory in Organic Reactions, Wiley: New York, 1984;Vol. 30, page 1. The analogous reaction of oxidative photocycling of1-aryl-2-pyrrilethylenes (II) to produce areno[e]indols (III) is lessdescribed in the bibliography, in spite of its unquestionable potential.The reason is that this reaction tends to give very small yields and ishighly dependent on the substrate. This small yield is often due to theoxidative decomposition in the reaction medium of the1-aryl-2-pyrrilethylenes (II) as starting products. A solution to thisproblem consists of the use of carefully studied reaction conditions togive the best yields in a given substrate. Hence, for example, M. P.Cava et al. in J. Org. Chem., 56, 2240 (1991) and cited references havecarried out these oxidative cyclings on some 1-aryl-2-pyrrilethylenes(II), irradiating them with ultraviolet light in the presence ofpalladium on carbon, silica-gel, triethylamine and p-nitrobenzoic acidin acetonitrile to reflux and an inert atmosphere, with very goodyields. These good yields are obtained however as a result of alaborious search for reaction conditions which end up being littleversatile; furthermore, these conditions may end up to be technicallycomplex to use. ##STR1##

On the other hand, the areno[e]indols (III) are intermediates useful forpreparing hexahydroareno[e]cyclopropa[c]indol-4-ones (IV.) Theseindolones have a great pharmaceutical interest as they contain thestructural unity of cyclopropa[c]indol-4-one which, among others D. L.Boger et al. in J. Am. Chem. Soc., 113, 2779 (1991) have proven that itis responsible for the antitumoral activity of the CC-1065 agent (V) andsynthesis analogues of the same. ##STR2##

The object of the present invention is to solve the problem raised inthe preparation of areno[e]indols (III) by photochemical irradiation inthe presence of 1-aryl-2-pyrrilethylene oxidants (II.)

The problems associated with the photochemical cycling of1-aryl-2-pyrrilethylenes (II) are solved in this invention by preparingcompounds of general structure (II) wherein the double central bond issubstituted by an arylsulfonyl group. This group acts by drawing outcharge and therefore stabilizing the 1-aryl-2-pyrrilethylene to which itis linked against undesired oxidations, which allows easy photocyclingthereof leading to an areno[e]indol substituted with an arylsulfonylgroup, that can be easily eliminated, if desired, by using a reducingagent capable of breaking the carbon sulfur bond.

DETAILED DESCRIPTION OF THE INVENTION

Just as is stated in the title hereof, the present invention refers tonew areno[e]indols, preparation method and application thereof asintermediates in the synthesis of products with antitumoral activity.Said new areno[e]indols have the general formula (I): ##STR3## wherein--Ar represents phenyl or substituted phenyl, Ar' represents a condensedradical of formula: ##STR4## wherein R, R¹, R², R³ may representhydrogen, halogen, a linear or branched alkyl, alkenyl or alkynylradical, a formyl, acyl, carboxy, akoxycarbonyl, aminocarbonyl,alkylaminocarbonyl, dialkylaminocarbonyl, cyano, hydroxy, alkoxy, amino,alkylamino, dialkylamino, acylamino or nitro radical and X representsoxygen, sulfur or a substituted or unsubstituted nitrogen and --Rrepresents an acyl group with 2 to 5 linear or branched chain carbonatoms.

In order to obtain the compounds of formula (I) one starts with a methyl2-arylsulfinylmethyl-N-methoxymethyl-4-pyrrolcarboxylate of generalformula (VI): ##STR5## wherein Ar has the meaning given above.

These compounds of formula (VI) can be prepared, in turn, starting withmethyl 2-formyl-pyrrolcarboxylate, a compound that is easily obtained byusing the process described by H. J. Anderson, C. E. Loader and A.Foster in Cam. J. Chem., 58, 2527 (1980.)

The treatment of methyl 2-formyl-4-pyrrolcarboylate with chloromethylethyl ether in the presence of a base and an adequate organic solventresults in methyl 2-formyl-N-methoxymethyl-4-pyrrolcarboxylate. The baseused is an alkoxide, a tertiary amine, an alkaline amide or anorganolytic compound; the organic solvent is an aprotic dipolar solvent,an ether or a hydrocarboned solvent; the reaction time is between 1 and40 hours and the temperature between -10° and 50° C.

The reduction of methyl 2-formyl-N-methoxymethyl-4-pyrrolcarboxylatewith a metal hydride in an organic solvent leads to the formation ofmethyl 2-hydroxymethyl-N-methoxymethyl-4-pyrrolcarboxylate. Normally thepreferred metal hydride is boron hydride and the organic solvent is analcohol with a low molecular weight such as methanol or ethanol. Thereaction temperature is generally between 0° and 40° C. and the timebetween 0.5 and 3 hours.

The treatment of methyl2-hydroxymethyl-N-methoxymethylpyrrol4-carboxylate with a substituted orunsubstituted benzenesulfinate in an acid medium gives rise to methyl2-aryl-sulfinylmetho-N-methoxymethyl-4-pyrrolcarboxylate of generalformula (VI) indicated above. In the same manner as thebenzenesulfinate, 1-toluenesulfinate can be used its counter-ion ionbeing a metallic cation, usually a sodium cation. The acid medium tendsto be determined by an organic acid that is normally used as thesolvent, for example, formic acid. The reaction temperature is normallybetween 0° and 50° C. and the time between 0.5 and 3 days.

The first step of the process of the invention includes reacting methyl2-arylsulfinilmetyl-N-methoxymethyl-4-pyrrolcarboxylate (VI) with astrong base in an inert solvent and then with an aromatic aldehyde,obtaining as a product of the reaction the compounds methyl2-(2-aryl-1-arylsulfonil-2-hydroxyethyl)-N-methoxymethylpyrrol-4-carboxylatecompounds of general formula: ##STR6## wherein Ar" represents an aryl,phenyl, pyrrolyl, furyl or thiophenyl group substituted up to threetimes by any of the above mentioned radicals R, R¹, R² and R³ and Ar hasthe meaning given above.

The strong base used to obtain the compound of formula (VII) can bealkaline amide, an alkyl-lithium or an aryl-lithium, preferably lithiumdiisopropylamide; the solvent has to be an inert solvent such as dialkylether, 1,4-dioxane or tetrahydrofuran, preferably tetrahydrofuran, andthe aldehyde an aromatic aldehyde, such as methyl2-formyl-N-methoxymethylpyrrol-4-carboxylate, 4-methoxybenzaldehyde or3,4,5-trimethoxybenzaldehyde.

The compounds of formula (VII) obtained are oxidized in an inert solventto give the corresponding ketone of general formula: ##STR7## wherein--Ar and --Ar" have the above cited meaning.

The oxidant used is 2,3-dicyano-5,6-dichloro-p-benzoquinone and theinert solvent benzene, toluene, xylene, 1,4-dioxane or chlorobenzene.

The ketone of general formula (VIII) is subjected to acylation bytreating it with a suitable base in an inert solvent and then with anacyl chloride as an acylating agent, obtaining the acylated derivate ofgeneral formula: ##STR8## wherein Ar, Ar" and R have the meaning givenabove.

The base used can be an amine, an alkaline amide, an alkyl-lithium or anaryl-lithium, preferably triethylamine; the inert solvent may bechloroform, dichloromethane or 1,2-dichloroethane and the acylatingagent a chloride of an acid having 2 to 5 linear or branched chaincarbon atoms, preferably acetyl chloride.

The compound of formula (IX) is subjected to a photochemical cyclingprocess in an organic solvent, preferably an alcohol with a lowmolecular weight such as methanol or ethanol, in the presence of anoxidant, such as oxygen associated catalytic iodine, and underultraviolet irradiation.

The compound obtained by this photochemical cycling process from theacylated derivative of formula (IX) is a compound of general formula(I), an intermediary product in the synthesis of compounds withantitumoral activity.

EMBODIMENTS OF THE INVENTION

The present invention is illustrated with the following example, thatare not intended to limit at all the scope of the applicability thereof.

In order to describe the physical data of the synthesized compounds thefollowing abbreviations are used:

m.p.: melting point

IR: infrared

UV: ultraviolet

¹ H--NMR: nuclear magnetic resonance

S: singlet

d: doblet

t: triplet

m: multiplet

J: coupling constant

MS: mass spectrum

ei: electronic impact

FAB: fast atom bombardment

M⁺ : molecular ion

.O slashed.: diameter

TS: tosyl=p-toluenesulfonyl

EXAMPLE OF PREPARATION Preparation of methylN-methoxymethyl-2-tosylmethyl-4-pyrrolcarboxylate

Step 1: Preparation of methyl2-formyl-N-methoxymethyl-4-pyrrolcarboxylate

A solution of 5.995 g of methyl 2-formyl-4-pyrrolcarboxylate is preparedin 60 mL of dry N,N-dimethylformamide, in a flask provided with acalcium chloride tube. To this solution magnetically stirred and cooledin an ice/water bath 7.323 g. of potassium tertbutoxide were added. Whenthe addition was ended, the reaction is left to room temperature and thestirring is maintained for 1.75 hours, after which the reaction iscooled again in an ice/water bath and 6 mL of chloromethyl ethyl theyare added slowly. After the addition is finished the reaction is left toroom temperature and the stirring is maintained for 18 hours.Thereafter, by fine layer chromatography analysis the existence of thestarting product is tested, so that, by repeating the same process usedabove, 1.864 g. of potassium tert-butoxide and 1.5 mL of chloromethylmethyl ether were added, leaving the stirring at room temperature for 16more hours.

The preparation is carried out by adding water and extraction with ethylacetate, followed by drying the organic phase with sodium sulfate andelimination of the solvent in a steam rotator, resulting in an oil thatis purified by silica gel column chromatography (25×3 cm .O slashed.),by elution with dichloromethanol/ethyl acetate (20:1.) 6.817 g. ofprotected pyrrol are obtained.

Yield: 88% m.p.: 65°-66° C. (petroleum ether:diethyl ether) IR(KBr,maximum γ): 1670, 1705, 2950, 3115 cm ⁻¹ UV (ethanol, maximum λ): 220,278 nm.

¹ H--NMR (CDCl₃): 3.34 (s, 3H, ArCH₂ OCH₃), 3.85 (s, 3H, ArCO₂ CH₃),5.67 (s, 2H, ArCH₂ OCH₃), 7.39 (d. 1H, J=1.6 Hz, ArH), 7.69 (s wide, 1H,ArH), 9.62 (d, 1H, J=0.8 Hz, ArCHO) ppm.

MS (e.i., m/e, %): 197 (M⁺, 29) 182 (M⁺. --CH₃, 100), 166 (M⁺. --OCH₃,28), 154 (M⁺. --CH₃ CO, 23.)

Elemental analysis for C₉ H₁₁ NO₄ : Calculated: % C=54.77: % H=5.62; %N=7.10 Found: % C=55.04: % H=5.65; % N=6.95

Step 2: Preparation of methyl2-hydroxymethyl-N-methoxymethyl-4-pyrrolcarboxylate 165 mg. NaBH₄ areadded to a magnetically stirred solution cooled in an ice/water bath of515 mg. of methyl 2-formyl-N-methoxymethyl-4-pyrrolcarboxylate in 8 mLof dry methanol, in a flask provided with a calcium chloride tube. Afterthe addition has been ended, stirring is maintaining for 1.5 hours.

Addition of water to the reaction mixture followed by elimination of themethanol in the steam rotor, extraction with ethyl acetate, drying theorganic phase with sodium sulfate and elimination of the solvent in thesteam rotor, gives rise to an oil, which is purified by silica gelcolumn chromatography (15×2 cm .O slashed.), by elution withdichloromethane/ethyl acetate (5:1), whereby 507 mg of the desiredalcohol are obtained.

Yield: 98% m.p.: 56°-57° C. (ethyl acetate:hexane) IR (KRr, maximum γ):1710, 2950, 3120, 3400 wide cm⁻¹ UV ethanol maximum λ): 208 225 260_(shoulder) nm ¹ H--NMR (CDCl₃): 3.29 (s, 3H, ArCH₂ OCH₃), 3.80 (s, 3H,ArCO₂ CH₃), 4.61 (s, 2H, ArCH₂ OH). 5.28 (s, 2H, ArCH₂ OCH₃), 6.60 (d,1H, J=1.6 Hz, ArH), 7.40 (d, 1H, J=1.7 Hz, ArH) ppm

MS (e.i., m/s, %): 199 (M⁺., 182 (M⁺. --OH, 3) 168 (M⁺. --OCH₃, 13) 45(CH₃ OCH₂ +, 100).

Elementary analysis for C₉ H₁₃ NO₄ : Calculated: % C=54.26: % H=6.57: %N=7.03 Found: % C=53.91: % H=6.82: % N=6.95

Step 3: Preparation of methylN-methoxymethyl-2-tosylmethyl-4-pyrrolcarboxylate

A solution of 438 mg. methyl2-hydroxymethyl-N-methoxymethyl-4-pyrrolcarboxylate and 1.881 g. ofsodium p-toluenesulfinate in 5 mL of aqueous 85% formic acid is stirredat room temperature for 23 hours.

Addition of water to the reaction mixture, followed by extraction withdichloromethane, drying of the organic phase with sodium sulfate andelimination of the solvent in the steam rotator, leads to a solid thatis purified by means of a silica gel column (15×1.5 cm, .O slashed.),elution with dichloromethane:ethyl acetate (20:1), whereby 702 mg. ofsulfone are obtained.

Yield: 95% m.p.: 104°-105° C. (ethyl acetate: petroleum ether) IR (KBR,maximum γ): 1705. 2940, 3120 cm⁻¹ IV ethanol, maximum λ): 202, 208, 226nm

¹ H--NMR (CDCl₃): 2.44 (s, 3H, ArCH₃), 3.17 (s, 3H, ArCH₂ OCH₃), 3.77(s. 3H, ArCO₂ CH₃), 4.42 (s, 2H, ArCH₂ Ts), 5.27 (s, 2H, ArCH₂ OCH₃).6.30 (d, 1H, J=1.3 Hz, ArH), 7.30 (d, 2H, J=8.2 Hz, ArH), 7.38 (d, 1H,J=1.7 Hz, ArH), 7.57 (d, 2H, J=8.2 Hz, ArH) ppm.

MS (e.i., m/s, %), 337 (M⁺., 0.3) 306 (M⁺. --OCH₃, 3), 1.82 (M⁺. --SO₂(C₆ H₄)CH₃, 100).

Elementary analysis for C₁₆ H₁₉ MO₅ S: Calculated: % C=56.96; % H=5.67;% N=4.15 Found: % C=56.83; % H=5.80; % N=3.86

EXAMPLE 1

1) Methyl2-[2-hydroxy-2-(4-methoxycarbonyl-N-methoxymethyl-2-pyrryl)-1-tosylethyl]-N-methoxymethyl-4-pyrrolcarboxylate

A solution of lithium diisoproplyamide is prepared by adding 0.8 mL of a2.7M solution of n-butyl-lithium in hexane on a solution of 0.31 mL ofdiisopropylamine in 20 mL of tetrahydrofuran. 600 mg. of methylN-methoxymethyl-2-tosylmethyl-4-pyrrolcarboxylate are added to thesolution of lithium diisopropylamide stirred magnetically and cooled to-75° C. The temperature of the resulting suspension is left to rise to-40° C. for 1.25 hours and on the generated red soluion 351 mg. ofmethyl 2-formyl-N-methoxymethyl-4-pyrrolcarboxylate are added. Thetemperature of the reaction mixture is left to rise to -15° C. for 2hours and 5 mL of hydrochloric acid 10% are added.

Addition of 20 mL of brine, followed by extraction with diethyl ether,drying of the organic phase with sodium sulfate and elimination of thesolvent in a steam rotator, leads to a solid residue that is purified onsilica gel column chromatography (18×2 cm .O slashed.), using an elutiongradient of dichloromethane/ethyl acetate increasing the proportion ofethyl acetate from 15 to 25%. 921 mg. of the condensation product isobtained as a sole diastereoisomer.

Yield: 97% m.p.: 180°-181° C. (ethyl acetate) IR (KBr, maximum γ: 1688,1715, 2950, 3120, 3460 cm⁻¹ UV (ethanol maximum): 205, 225 _(shoulder),255 _(shoulder) nm

¹ H--NMR (CDCl₃): 2.40 (S, 3H, ArCH₃), 3.08 (s, 3H, ArCH₂ OCH₃), 3.17(s, 3H, ArCH₂ OCH₃), 3.67 (s, 3H, ArCO₂ CH₃) 3.71 (s, 3H, ArCO₂ CH₃),4.06 (d, 1H, J=3.7 Hz, ArCH(R)OH) 4.70 (d, 1H, J=11.4 Hz, ArCH₂ OCH₃),5.09 (m, 2H, ArCH₂ OCH₃ and ArCH(Ts)R) 5.36 (d, 1H J=11.5 Hz ArCH₂OCH₃), 5.37 (d, 1H, J=10.7 Hz, ArCH₂ OCH₃), 5.54 (dd, 1H, J=2.6 and 10.4Hz, ArCH(OH)R), 6.42 (d, 1H, J=1.3 Hz, ArH), 6.49 (d, 1H, J=1.5 Hz,ArH), 7.18 (m, 2H, ArH), 7.25 (d, 2H, J=7.9 Hz, ArH) 7.57 (d, 2H, J=8.3Hz, ArH) ppm.

MS (FAB, m/s, %): 535 (M+1H₂ O, 29), 503 (M+1--CH₃ OH, 28), 489(M+1--CH₃ OCH₃,6), 379 (M+1--CH₃ (C₆ H₄)SO₂ H, 4), 362 M+1+H₂ O--CH₃ (C₆H₄)SO₂,100), 348 (M+1--CH₃ (C₆ H₄)SO₂ H--OCH₃, 21), 333 (M+1--CH₃ (C₆H₄)SO₂ H--CH₃ OCH₃, 9) 315 (M+1--CH₃ (C₆ H₄)SO₂ H--CH₃ OCH₃ --H₂ O, 61)182 (ArCH₂ A, 83).

Elementary analysis for C₂₅ H₃₀ N₂ O₉ S: Calculated: % C=56.17; %H=5.66; % N=5.24% S=6.00 Found: % C=55.92; 4 H=5.58; % N=5.22; % S=6,36

2) Methyl2-[2-hydroxy-2-(4-methoxyphenyl)-1-tosylethyl]-N-methoxymethyl-4-pyrrolcarboxylate

A solution of lithium diisopropylamide is prepared by adding 4.21 mL ofa 2.4M solution of -n-butyl-lithium in hexanes on a 1.5 mL solution ofdiisopropylaminde in 100 mL of tetrahydrofuran. 2.9 g. of methylN-methoxy-2-tosylmethyl-4-pyrrolcarboxylate are added to a solution oflithium diisopropylamide stirred magnetically and cooled to -50° C. 2hours later 1.06 mL of methoxybenzaldehyde are added on the ceneratedred solution. 1 hour later HCl 10% is added.

Addition of brine, followed by extraction with diethyl ether, drying theorganic phase with sodium sulfate and elimination of the solvent in asteam rotator, leads to a dry residue that is purified by silica gelcolumn chromatography (27×3.5 cm .O slashed.), by elution withdichloromethane/ethyl acetate (3:1.) 3.58 g. of the condensation productare obtained as two diasteroeoisomers in the ratio of 3:1.

Yield: 88% IR (film, maximum γ): 1560, 1610, 1710, 2960, 3480 cm⁻¹ UV(ethanol, maximum λ): 204, 328 nm

¹ H--NMR (CDCl₃): 2.37 (s, ArCH₃, minority), 2.40 (s, CH₂ OCH₃,minority), 2.42 (s, ArCH₃, majority), 2.50 (s, CH₂ OCH₃, majority), 3.70(s, CO₂ CH₃, majority+minority), 3.79 (s, ArOCH₃, majority+minority),4.05 (d, J=11.3 Hz, NCH₂ OCH₃, minority), 4.39 (d, J=11.13 Hz, NCH₂OCH₃, minority). 4.39 (d, J=11.3 Hz, NCH₂ OCH₃ majority), 4.48 (d,J=11.3 Hz, NCH₂ OCH₃, minority) 4.56 (d, J=1.9 Hz, HCOH, minority), 4.75(d, J=9.8 Hz, HCOH, majority), 4.78 (d, J=11.3 Hz, NCH₂ OCH₃, majority),5.33 (d, J=9.8 Hz, CHTs, majority), 5.80 (d, J=1.9 Hz, CHTs, minority),6.61 (d, J=1.4 Hz, ArH, majority), 6.68 (d, J=8.7 Hz, ArH, majority),6.71 (d, J=8.6 Hz, ArH, minority), 7.00 (d, J=1.4 Hz, ArH,majority+minority), 7.02 (d, J=8.6 Hz, ArH, minority), 7.14 (d, J=8.7Hz, ArH. majority), 7.27 (d, J=8.3 Hz, ArH, majority), 7.37 (d, J=1.4Hz, ArH, minority), 7.57 (d, J=8.3 Hz, ArH, majority+minority), 7.64 (d,J=8.3 Hz, ArH, minority)

MS (FAB, m/s, %): 474 (M+1.7), 476 (M+1--H₂ O, 63) 442 (M+1--HOCH₃, 3)318 (M+1--TsH,24), 301 (M+1--H₂ O--TsH, 70 ), 286 (M+1--HOCH₃ --TsH, 67)258 (M+1--HOCH₃ --TsH--CO, 23. )

Elementary analysis for C₂₄ H₂₇ NO₇ S: Calculated: % C=60.87; % H--5.75;% N=2.96 Found: % C=61.32; % H=5.96: % N=2.72

3) Methyl2-[2-hydroxy-2-(3,4,5-trimethoxyphenyl)-1-tosylethyl]-N-methoxymethyl-4-pyrrolcarboxylate

A solution of lithium diisoproplylamide is prepared by adding 4.8 mL ofa solution of 2.44M n-butyl-lithium in hexanes on a solution of 1.9 Mlof diisopropylamine in 70 mL of tetrahydrofuran. 3.0 g. of methylN-methoxymethyl-2-tosylmethyl-4-pyrrolcarboxylate are added to thesolution of lithium diisopropylamide stirred magnetically and cooled to-80° C. The resulting suspension is left stirring at -50° C. for 2.3hours and 1.75 g. of 3,4,5-trimethoxybenzaldehyde are added to thegenerated red solution. After 1.5 hours of stirring at -50° C. thereaction is cooled to -70° C. and 100 ml. of hydrochloric acid 10% areadded.

Extraction with diethyl ether, followed by drying of the organic phasewith sodium sulfate and elimination of the solvent in the steam rotator,leads to a solid residue that is purified by recrystallization ofdichloromethanecyclohexane, giving a first fraction that is mixed with asecond fraction of product, result of concentrating the mother liquors,dissolving the residue in methanol, adding cyclohexane and filtering theresulting precipitate. 3,15 g. of the condensation product are obtainedas two two diasteroisomers in the ratio of 3:1.

Yield: 66% m.p. 80°-90° C. IR (film, maximum γ): 1590, 1710, 2950, 3000.3470 cm⁻¹ UV (ethanol maximum λ): 282 nm

¹ H--NMR (CDCl₃): 2.34 (d, J=1.3 Hz, ArCH₃ minority), 2.40 (t, J=1.5 Hz,ArCH₃ majority), 3.85-3.65 (m, ArOCH₃ +CO₂ CH₃ +CH₂ OCH₃,majority+minority), 3.98 (d, J=1.7 Hz, NCH₂ OCH₃ minoirty). 4.43 (d,J=10.8 Hz, NCH₂ OCH₃ majority), 4.45 (d, J=1.7 Hz, NCH₂ OCH₃ minority),

4.76-4.62 (m, HCOH+HCTs, majority+minority), 5.32 (d, J=9.5 Hz, NCH₂OCH₃ majority), 5.85 (s, OH) 633 (d, J=1.1 Hz, ArH minority), 6.44 (d,J=1.3 Hz, ArH majority), 6.73 (s, ArH majority), 6.98 (t, J=1.6 Hz, ArHmajority), 7.08 (t, J=1.6 Hz, ArH minority), 7.24 (d, ArH minoirty),7.25 (dd, ArH majority), 7.34 (s, ArH minority), 7.57 (dd, J=1.5 and 8.4Hz, ArH majority), 7.61 (d, J=6.9 Hz, ArH minority) ppm.

EXAMPLE 2

1) Methyl2-[2-(4-methoxycarbonyl-N-methoxymethyl-2-pirryl)-2-oxo-1-tosylethyl]-N-,ethoxymethyl-4-pyrrolcarboxylate

A mixture of 2.35 g. of methyl2-[2-hydroxy-2-(4-methoxycarbonyl-N-methoxymethyl-2-pyrril)-1-tosylethyl]-N-methoxymethyl-pyrrolcarboxylateand 2.51 g. of 2,3-dicyano-5,6-dichloro-p-benzoquinone in 25 mL of drybenzene is heated to reflux under argon for 24 hours.

Addition of 100 mL of a saturated solution of Na₂ S₂ O₅, followed byextraction with dichloromethane, washing the organic solution with asaturated Na₂ S₂ O₅ solution, drying with sodium sulfate andconcentration of the same, gives rise to an oil that is purified bysilica gel column chromatography (20×2 cm .O slashed.), by elution withethyl acetate/hexane (1:1) to give rise to 2.20 g. of the desiredketone.

Yield: 92% m.p.: 58°-60° C. (ethyl acetate-hexane) IR (KBr, maximum γ):1670, 1718, 2950, 3120 cm⁻¹ UV (ethanol, maximum λ): 208, 222_(shoulder), 293 nm

¹ H--NMR (CDCl₃): 2.39 (s, 3H, ArCH₃); 3.27 (s, 6H, ArCH₂ OCH₃), 3.71(s, 3H, ArCO₂ CH₃), 3.79 (s, 3H, ArCO₂ CH₃), 4.92 (d, 1H, J=11.1 Hz,ArCH₂ OCH₃), 5.58 (d, 1H, J=10.2 Hz, ArCH₂ OCH₃), 5.61 (d, 1H, J=10.2Hz, ArCH₂ OCH₃), 6.04 (d, 1H, J=11.1 Hz, ArCH₂ OCH₃), 6.27 (s, 1H, ArCH(Ts)R), 6.47 (d, 1H, J=1.7 Hz, ArH), 7.22 (d, 2H, J=8.2 Hz, ArH), 7.42(d, 1H, J=1.8 Hz, ArH), 7.50 (d, 2H, J=8.3 Hz, ArH), 7.59 (d, 1H, J=1.7Hz, ArH), 7.64 (d, 1H, J=117 Hz, ArH) ppm.

MS (e.i., m/s %): 532 (M⁺., 1) 501 (M⁺. --CH30.8) 377 (M⁺. --CH₃ (C₆H₄)SO₂, 94), 395 (M⁺. --CH₃ O--CH₃ (C₆ H₄)SO₂ H. 99) 317 (M⁺. --CH₃O--CH₃ (C₆ H₄)SO₂ H--CO, 100), 196 (ArCO⁺, 44), 182 (ArCH₂ +, 22), 139(CH₃ (C₆ H₄)SO⁺., 11) 91 (CH₃ (C₆ H₄)⁺, 16).

Elementary analysis for C₂₅ H₂₈ N₂ O₉ S: Calculated: % C=56.38; %H=5.30: % N=5.26: S=6.02 Found: % C=56.08; % H=5.45; N=5.13: % S=5.98

2) Methyl2-[2-(4-methoxyphenl)-2-oxo-tosylethyl]-N-methoxymethyl-4-pyrrolcarboxylate

A mixture of 1.42 g. of methyl2-[2-hydroxy-2-(4-methoxyphenyl)-1-tosylethyl]-N-methoxymethyl-4-pyrrolcarboxylateand 1.7 g. of 2,3-dicyano-5,6-dichloro-p-benzoquinone in 70 mL of drytoluene is heated to reflux under argon for 12 hours.

Addition of a saturated solution of Na₂ S₂ O₅, followed by extractiondichloromethane, washing the organic solution with a saturated solutionof Na₂ S₂ O₅, drying with sodium sulfate and concentrating the same,gives rise to an oil that can be purified by silica gel columnchromatography (35×3 cm .O slashed.), by elution with ethylacetate/hexane (1:1) to give rise to 1,27 g. of the desired ketone.

Yield: 90% m.p.: 108°-109° C. IR (film, maximum γ): 1570, 1600, 1680.1715 cm ⁻¹ UV (ethanol, maximum λ): 294, 222 nm)

¹ H--NMR (CDCl₃): 2.44 (s, 3H, ArCH₃), 3.26 (s, 3H, NCH₂ OCH₃), 3.73 (s,3H, CO₂ CH₃), 3.85 (s, 3H, ArOCH₃), 4.97 (d, 1H, J=11.1 Hz, NCH₂ OCH₃),6.24 (d, 1H, J=11.1 Hz, NCH₂ OCH₃), 6.39 (d, 1H, J=1.8 Hz, ArH), 6.54(s, 1H, HCTs), 6.89 (d, 2H, J=9.0 Hz, ArH), 7.26 (d, 2H, J=8.3 Hz, ArH),7.46 (d, 1 H, J=1.8 Hz, ArH), 7.52 (d, 2H, J=8.3 Hz, ArH), 7.96 (d, 2H,J=9.0 Hz, ArH) ppm.

MS (e.i., m/s, %) 471 (M⁺., 3), 316 (M⁺. --TsH 100) 135 (CH₃ O(C₆H₄)CO⁺, 49) 91 (CH₃ C₆ H₄ +, 19).

3) Methyl2-[2-(3,4,5-trimethoxyphenyl)-2-oxo-1-tosylethyl]-N-methoxymethyl-4-pyrrolcarboxylate

A mixture of 2.65 g. of methyl2-[2-hydroxy-2-(3,4,5-trimethoxyphenyl)-1-tosylethyl]-N-methoxymethyl-4-pyrrolcarboxylateand 3,95 g. of 2.3-dicyano-5,6-dichloro-p-benzoquinone in 90 mL of drytoluene is dried to reflux under argon for 9 hours.

The elimination of toluene gives rise to a dark residue that isdissolved in dichloromethane. The resulting solution is filtered, washedwith an aqueous saturated Na₂ SO3 solution and concentrated, yielding aresidue that is purified by silica gel column chromatography, by elutionwith dichloromethane-ethyl acetate (9:1), giving rise to 1.63 g. of thedesired ketone.

Yield: 62% ¹ H--NMR (CDCl₃): 2.46 (s, 3H, ArCH₃), 3.27 (s, 3H, NCH₂OCH₃), 3.75 (s, 3H, CO₂ CH₃), 3.84 (s, 6H, ArOCH₃), 3.94 (2, 3H,ArOCH₃), 5.00 (d, 1H, J=11 Hz, NCH₂ OCH₃), 6.26 (d, 1H, J=11 Hz, NCH₂OCH₃), 6.36 (d, 1H, J=1.7 Hz, ArH), 6.54 (s, 1H, HCTs), 7.27 (s, 2H,ArH), 7.28 (d, 2H, J=8.4 Hz, ArH), 7.48 (d, 1H, J=1 Hz, ArH), 7.5 (d,2H, J=8.4 Hz, ArH) ppm.

EXAMPLE 3

1) Methyl2-[2-acetoxy-2-(4-methoxycarbonyl-N-methoxymethyl-2-pyrril)-1-tosylethenyl]-N-methoxymethyl-4-pyrrolcarboxylate

4.4 mL of acetyl chloride are slowly added to a solution, magneticallystirred and kept at -40° C. under argon, of 4.67 g. of methyl2-[2-(4-methoxycarbonyl-N-methoxymethyl-2-pirryl)-2-oxo-1-tosylethyl]-N-methoxymethyl-4-pyrrolcarboxylateand 12.1 mL of triethylamine in 60 mL of dry dichloromethane.

After 2.25 hours, 100 mL of hydrochloric acid 10% are added andextracted with dichloromethane. Drying with sodium sulfate andconcentrating the organic phase yields an oil that is purified by silicagel column chromatography (18×3 cm .O slashed.), by elution with ahexane-ethyl acetate gradient of 40 to 60% in ethyl acetate. 4.96 g. ofenol acetate.

Yield: 98% m.p. 59°-61° C. (Dichloromethane-ethyl acetate) IR (film,maximum γ): 1720, 1785, 2880, 2960 cm⁻¹ UV (ethanol, maximum λ): 205,302, 315_(shoulder) nm

¹ H--MMR (CDCl₃): 2.32 (s, 3H, ArOCOCH₃), 2.42 (s, 3H, ArCH₃), 2.99 (s,3H, NCH₂ OCH₃), 3.20 (s, 3H, NCH₂ OCH₃) 3.69 (s, 3H, ArCO₂ CH₃), 3.76(s, 3H, ArCO₂ CH₃), 4.82 (d, 1H, J=10.6 Hz, ArCH₂ OCH₃), 4.99 (d, 1H,J=10.6 Hz, ArCH₂ OCH₃), 5.13 (d, 1H, J=10.6 Hz, ArCH₂ OCH₃), 5.23 (d,1H, J=10.6, ArCH₂ OCH₃), 6.26 (d, 1H, J=1.8 Hz, ArH), 6.47 (d, 1H, J=1.8Hz, ArH), 7.27 (d, 2H, J=8.1 Hz, ArH), 7.31 (d, 1H, J=1.7 Hz, ArH), 7.40(d, 1H, J=1.8 Hz, ArH), 7.62 (d, 2H, J=8.3 Hz, ArH) ppm.

MS (e.i., m/s, %): 574 (M⁺., 4), 543 (M⁺. --CH₃ O, 7) 532 (M⁺. --CH₂ CO,75) 500 (M⁺. --CH₃ OH----CH₂ CO, 20), 377 (M⁺. --CH₂ CO--CH₃ (C₆ H₄)SO₂,32), 345 (M⁺. --CH₃ OH--CH₂ CO--CH₃ (C₆ H₄) SO₂, 90), 317 (M⁺. --CH₃OH--CH₂ CO--CH₃ (C₆ H₄)SO₂ --CO, 54), 196 (ArCO⁺, 41) 182 (ArCH₂ +100),139 (CH₃ (C₆ H₄)SO⁺., 24) 91 (CH₃ (C₆ H₄)+, 18.)

2) Methyl 2-[2-acetoxy-2-(4-methoxyphenyl)-1-tosylethenyl]-N-methoxymethyl-4-pyrrolcarboxylate

1.34 mL of acetyl chloride are slowly added on a solution, magneticallystirred and kept at -40° C. under argon, of 1.27 g. of methyl2-[2-(4-methoxyphenyl)-2-oxo-1-tosylethyla-N-methoxymethyl-4-pyrrolcarboxylateand 3.76 mL of triethylamine in 60 mL of dry dichloromethane.

After 2 hours 20 mL of hydrochloric acid 10% are added and extractedwith dichloromethane. Drying with sodium sulfate and concentration ofthe organic phase gives an oil that is purified by silica gel columnchromatography (30×3 cm .O slashed.), by elution with hexane-ethylacetate (1:1). 1.34 g. of enol acetate are obtained as the sole isomer.

Yield: 97% m.p. 152.5°-153.5° C. IR (film, maximum γ): 1510, 1550, 1595,1780, 2955 cm⁻¹ UV (ethanol, maximum λ): 298, 212 nm

¹ H--NMR (CDCl₃): 2.42 abd 2,43 (s, 3H, ArCH₃ and ArOCOCH₃), 3.00 (s,3H, NCH₂ OCH₃), 3.74 (s, 3H, ArCO₂ CH₃), 3.79 (s, 3H, ArOCH₃), 4.64 (d,1H, J=10.3 Hz, NCH₂ OCH₃), 5.00 (d, 1H, J=10.3 Hz, NCH₂ OCH₃), 6.44 (d,1H, J=1.7 Hz, ArH), 6.69 (d, 2H, J=9.0 Hz, ArH), 7.12 (d, 2H, J=9.0 Hz,ArH), 7.28 (d, 2H, J=8.3 Hz, ArH), 7.54 (d, 1H, J=1.7 Hz, ArH), 7.68 (d,1H, J=8.3 Hz, ArH)

MS (FAB, m/s, %): 514 (M+, 9), 471 (M+1--CH₂ CO, 37) 440 (M+1--CH₂CO--CH₂ OCH₃, 30) 135 (CH₃ O(C₆ H₄)⁺, 100) 284 (M+1--CH₂ CO--CH₂ OCH₃--TsH, 33).

3) Methyl2-[2-acetoxy-2-(3,4,5-trimethoxyphenyl)-1-tosylethenyl]-N-methoxymethyl-4-pyrrolcarboxilate

0.24 mL of acetyl chloride are slowly added to a solution, magneticallystirred and kept at -40° C. under argon, of 99 mg. of methyl2-[2-(3,4,5-trimethoxyphenyl)-2-oxo-1-tosylethyl]-N-methoxymethyl-4-pyrrolcarboxylateand 0.24 mL of triethylamine in 5 mL of dry dichloromethane.

After 5.7 hours 5 mL of hydrochloric acid 10% are added and extractedwith dichloromethane. Drying with sodium sulfate and concentration ofthe organic phase gives rise to an oil that is purified by silica gelcolumn chromatography (15×1 cm .O slashed.), by elution withhexane-ethyl acetate (1:1). 101 mg. of enol acetate are obtained as amixture of isomers in a ratio of 5:1.

Yield: 95% IR (film, maximum γ): 1580. 1715, 1775. 2740, 2945, 2955,3055, 3120 cm⁻¹ UV (ethanol, maximum λ): 304 nm.

¹ H--NMR (CDCl₃) (majority isomer) 2.43 and 2.42 (s, 3H, ArCH₃ andArOCOCH₃), 3.12 (s, 3H, NCH₂ OCH₃), 3.79-374 (singlets, 6H, ArOCH₃ andArOCH₃), 4.94 (d, 1H, J=10.1 Hz, NCH₂ OCH₃), 5.12 (d, 1H, J=10.5 Hz,NCH₂ OCH₃), 6.39 (d, 1H, J=1.7 Hz, ArH), 7.27 (s, 2H, ArH), 7.32 (d, 2H,J=8.4 Hz, ArH), 7.48 (d, 1H, J=1.8 Hz, ArH), 7.70 (d, 2H, J=8.3 Hz, ArH)ppm.

EXAMPLE 4

1) Dimethyl5-acetoxy-3,6-bis(methoxymethyl)-4-tosyl-3,6-dihydropyrrol[3,2-e]indol-1,8-dicarboxylate

An aerated solution of 2.30 g. of methyl2-[2-acetoxy-2-(4-methoxycarbonyl-N-methoxymethyl-2-pirryl)-1-tosylethenyl]-N-methoxymethyl-4-pyrrolcarboxylateand 160 mg. of iodine in 225 mL of ethanol, introduced in aphotochemical Pyrex glass reactor is irradiated for 3.5 hours withultraviolet light produced by a Hanowia 400 W lamp.

Addition of an aqueous saturated solution of Na₂ S₂ O₅ until the colordue to the iodine disappears, followed by elimination of the ethanolunder reduced pressure, extraction with dichloromethane, drying of theorganic phase with sodium sulfate and elimination of the solvent, givesrise to a residue that is purified by silica gel column chromatography(19×2 cm .O slashed.), by elution with hexane-ethyl acetate (1:1) togive 2.18 g. of the desired pyrrolindol.

Yield: 95% m.p.: 128°-130° C. (hexane-ethyl acetate) IR (film, maximumγ): 1720, 1790, 2950 cm⁻¹ UV (ethanol, maximum λ): 202, 215, 237, 264,326 nm

¹ H--NMR (CDCl₃): 2.26 (s, 3H, ArOCOCH₃), 2.35 (s, 3H, ArCH₃). 2.96 (s,3H, NCH₂ OCH₃), 3.14 (s, 3H, NCH₂ OCH₃), 3.82 (s, 3H, ArCO₂ CH₃), 3.83(s, 3H, ArCO₂ CH₃), 4.97 (d, 1H, J=10.9 Hz, NCH₂ OCH₃), 5.79 (m, 3H,NCH₂ OCH₃), 7.18 (d, 2H, J=8.1 Hz, ArH), 7.55 (d, 2H, J=8.3 Hz, ArH),(s, 1H, ArH), 7.96 (s, 1H, ArH) ppm.

MS (e.i., m/s, %): 572 (M⁺. --CH₂ O, 100), 498 (M⁺. --CH₂ O--CH₃ OH,49), 433 (M⁺. --CH₃ (C₆ H₄)SO, 33) 402 (M⁺. --CH₃ (C₆ H₄)SO--CH₃ O, 67),375 (M⁺. --CH₂ CO--CH₃ (C₆ H₄)SO₂, 67), 343 (M⁺. CH₂ CO--CH₃ (C₆ H₄)SO₂--CH₃ OH. 38), 139 (CH₃ (C₆ H₄)SO⁺, 29) 91 (CH₃ (C₆ H₄)⁺, 23).

Elementary analysis for C₂₇ H₂₈ N₂ O₁₀ S: Calculated: % C=56.64, %H=4.93; % H=4.89; % S=5.60 Found: % C=56.89; % H=5.05; % N=5.01; %S=5.66

2) Methyl5-acetoxy-8-methoxy-N-methoxymethyl-4-tosylbenzo[e]indol-1-carboxylate

An aerated solution of 560 mg. of methyl2-[2-acetoxy-2-(4-methoxyphenyl)-1-tosylethenyl]-N-methoxymethyl-4-pyrrolcarboxylateand 40 mg. of iodine in 100 mL of ethanol introduced in a photochemicalPyrex glass reactor, is irradiated for 17 hours with ultraviolet lightproduced by a Hanowia 400 W lamp.

Addition of an aqueous saturated solution of Na₂ S₂ O₅ until the colordue to the iodine disappears, followed by elimination of the ethanolunder reduced pressure, extraction with dichloromethane, drying of theorganic phase with sodium sulfate and elimination of the solvent givesrise to a residue that is purified by silica gel Column chromatography(23×1 cm .O slashed.), by elution with hexane-ethyl acetate (1:1) togive 457 mg. of the desired pyrrolindol.

Yield: 82% m.p.: 163°-164° C. IR (KBr, maximum): 1510, 1620, 1710, 1780,2950, 3120 cm⁻¹ UV (ethanol, maximum γ): 216, 272, 326 nm

¹ H--NMR(CDCl₃): 2.37 (s, 3H, ArCH₃), 2.39 (s, 3H, ArOCOCH₃), 2.95 (s,3H, ArCH₂ OCH₃), 3.95 (s, 3H, ArCO₂ CH₃), 4.06 (s, 3H, ArCO₂ CH₃) 5.86(s, 2H, ArCH₂ OCH₃), 7.13 (dd, 1 H, J=2.5 and 9.2 Hz, ArH), 7.2 (d, 2H,J=8.2 Hz, ArH), 7.59 (d, 2H, J=8.2 Hz, ArH), 7.60 (s, 1H, ArH), 8,24 (s,1H, ArH), 9.42 (d, 1H, J=2.5 Hz, ArH) ppm

MS (e.i., m/s, %): 511 (M⁺., 11), 469 (M⁺. --CH₂ CO, 100), 437 (M⁺.--CH₂ CO--CH₃ OH, 35), 315 (M⁺. --CH₂ CO--Ts. 40), 139 (CH₃ (C₆ H₄)SO⁺.,26), 91 (CH₃ (C₆ H₄)⁺., 12).

3) Methyl5-acetoxy-7,8,9-trimethoxy-N-methoxymethyl-4-tosylbenzo[3]indol-1-carboxylate

An aerated solution of 101 mg. of methyl2-[2-acetoxy-2-(3,4,5-trimethoxyphenyl)-1-tosylethenyl]-N-methoxymethyl-4-pyrrolcarboxylateand 9 mg. of iodine in 30 mL of ethanol, introduced in a photochemicalPyrex glass reaction, is irradiated for 2.6 hours with ultraviolet lightproduced by a Hanowia 400 W lamp.

Addition of an aqueous saturated solution of Na₂ S₂ O₅ until the colordue to the iodine disappears, followed by elimination of the ethanolunder reduced pressure, extraction with dichloromethane, drying of theorganic phase with sodium sulfate and elimination of the solvent, givesrise to a residue that is purified by silica gel column chromatography,by elution with a dichloromethane-ethyl acetate gradient, increasing theproportion of ethyl acetate from 0 to 10%, to give 32 mg. of the desiredpyrrolindol.

Yield: 32% UV (ethanol, maximum γ): 228, 256, 336 nm.

¹ H--NMR (CDCl₃): 2.39 (s, 6H, NCH₂ OCH₃ and ArCH₃), 2.95 (s, 3H,ArOCOCH₃), 3.73 (s, 3H, ArOCH₃), 3.84 (s, 3H, ArOCH₃), 3.90 (s, 3H,ArCO₂ CH₃), 4.06 (s, 3H, ArOCH₃), 5.84 (s, 2H, NCH₂ OCH₃), 6.79 (s, 1H,ArH), 7.25 (d, 2H, J=8.5 Hz, ArH), 7.67 (d, 2H, J=8.4 Hz, ArH), 7.74 (s,1H, ArH) ppm.

We claim:
 1. A preparation method of new areno[e]indols, useful asintermediates in the synthesis of products with antitumoral activity, offormula: ##STR9## wherein: --Ar represents phenyl or substituted phenyl--Ar' represents a condensed radical of formulae: ##STR10## wherein R,R¹, R², R³ represent a hydrogen, a halide, a linear or branched alkyl,alkenyl or alkynyl radical, a formyl, acyl, carboxy, alkoxycarbonyl,aminocarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl, cyano, hydroxy,alkoxy, amino, alkylamino, dialkylamino, acylamino or nitro radical; andX represents a substituted or unsubstituted nitrogen; whose methodcomprises the following steps:a) reacting a compound of general formula(VI): ##STR11## wherein Ar represents phenyl or substituted phenyl, witha strong base in an inert solvent and then with an aldehyde of formulaAr"--CHO wherein Ar" represents a phenyl, pyrrolyl, furanyl orthiophenyl group substituted up to three times by any of the above citedradicals for R, R¹, R² and R³, obtaining as a reaction product acompound of general formula: ##STR12## wherein Ar and Ar" have themeaning given above; b) oxidizing the compounds of general formula (VII)obtained in step a) in an inert solvent to obtain the correspondingketone of general formula: ##STR13## wherein Ar and Ar" have the meaninggiven above; c) reacting the ketone of general formula (VIII) of step b)with a strong base in a suitable solvent and then with acyl chloride ofgeneral formula ClCOR obtaining products of general formula: ##STR14##wherein Ar, Ar" and R have the meaning given above; d) subjecting thecompounds of general formula (IX) obtained in step c) to a photochemicalcycling process in an organic solvent in the presence of an oxidant andsource of ultraviolet light, finally obtaining compounds of generalformula (I).
 2. Method according to claim 1, wherein in step a) the baseis an alkaline amide, alkyl-lithium or aryl-lithium; the inert solventis dialkyl ether, 1,4-dioxane or tetrahydrofuran; the reaction time isbetween 0.5 and 5 hours and the reaction temperature is between -80° and0° C.
 3. Method according to claim 2, wherein the base used is lithiumdiisopropylamide and an aromatic aldehyde is methyl2-formyl-N-methoxymethyl-4-pyrrolcarboxylate, 4-methoxybenzaldehyde or3,4,5-trimethoxybenzaldehyde.
 4. Method according to claim 1, wherein instep b) an oxidant used is 2,3-dicyano-5,6-dichloro-p-benzoquinone; theinert solvent is an aromatic solvent or 1,4-dioxane; the reaction timeis between 7 and 24 hours and the reaction temperature is between roomtemperature and the reflux temperature of the solvent.
 5. Methodaccording to claim 4, wherein the aromatic solvent used is benzene,toluene, xylene or chlorobenzene.
 6. Method according to claim 1,wherein in step c) the base used is an amine, an alkaline amide, analkyl-lithium or an aryl-lithium; an inert solvent is chloroform,dichloromethane or 1,2-dichloroethane an acylating agent is a chlorideacid of 2 to 5 linear or branched chain carbon atoms; the reaction timeis between 1 and 6 hours and the temperature between -50° C. and roomtemperature.
 7. Method according to claim 6, wherein the base istriethylamine, the solvent is dichloromethane, the acylating agent isacetyl chloride and the temperature is -40° C.
 8. Method according toclaim 1, wherein in step d) the solvent is an alcohol with a lowmolecular weight; the oxidant is oxygen associated to a catalyticiodine; the reaction temperature is between room temperature and theboiling point of the solvent and the reaction times are between 1 and 19hours.
 9. Method according to claim 8, wherein the solvent is ethanol.10. Method according to claim 1, wherein the compound of formula (VI)used as a starting product in step a) is obtained, in turn, by means ofthe following steps:a) reacting a methyl 2-formyl-4-pyrrolcarboxylatewith chloromethyl-methyl-ether in the presence of a base and a suitableorganic solvent, obtaining as a reaction product methyl2-formyl-N-methoxymethyl-4-pyrrolcarboxylate; b) reducing the methyl2-formyl-N-methoxymethyl-4-pyrrolcarboxylate obtained in step a) with ametal hydride in an organic solvent to obtain methyl2-hydroxymethyl-N-methoxymethyl-4-pyrrolcarboxylate; c) reacting themethyl 2-hydroxymethyl-N-methoxymethyl-4-pyrrolcarboxylate obtained instep b) with a substituted or unsubstituted benzenesulfinate in an acidmedium to finally obtain the compounds of general formula (VI). 11.Method according to claim 10, wherein in step a) the base used is analkoxide, a tertiary amine, an alkaline amide or an organolyticcompound; the organic solvent is an aprotic dipolar solvent, ahydrocarbonaceous solvent or ether; the reaction time is between 1 and40 hours and the temperature is between -10° and 50° C.
 12. Methodaccording to claim 11, wherein the base used is potassium tert-buthoxideand the organic solvent is N,N-dimethylformamide.
 13. Method accordingto claim 10, wherein in step b) the metal hydride is boron hydride andthe organic solvent is an alcohol with a low molecular weight. 14.Method according to claim 13, wherein the boron hydride is sodiumborohydride; the organic solvent is methanol; the reaction temperatureis between 0° and 40° C. and the reaction time is between 0.5 and 3hours.
 15. Method according to claim 10, wherein in step c), thesubstituted or unsubstituted benzenesulfinate is p-toluenesulfinate; acontra-cation of the sulfinate is a metal cation and the acid medium iscomprised of an organic acid used as a solvent.
 16. Method according toclaim 15, wherein the contra-cation of the sulfinate is the sodiumcation: the organic acid used as a solvent is aqueous formic acid 85%;the reaction temperature is between 0° and 50° C. and the reaction timeis between 0.5 and 3 days.